Pumps for pumping molten metal are used in furnaces in the production of metal articles. Common functions of pumps are circulation of molten metal in the furnace or transfer of molten metal to remote locations along transfer conduits or risers that extend from a base of the pump to the remote location. Die casting facilities are one example of a typical use of a molten metal transfer pump. Particularly, a molten metal transfer pump is used as one component in a die casting process to move molten metal from a furnace to a mold.
A traditional molten metal transfer pump is described in U.S. Pat. No. 6,286,163, the disclosure of which is herein incorporated by reference. Referring to FIG. 1, the molten metal pump is indicated generally by the reference numeral 10. The pump 10 is adapted to be immersed in molten metal contained within a vessel 12. The vessel 12 can be any container containing molten metal, although the vessel 12 as illustrated is an external well of a reverberatory furnace 13. The pump 10 has a base member 14 within which an impeller (not shown) is disposed. The impeller includes an opening along its bottom or top surface that defines a fluid inlet for the pump 10. The impeller is supported for rotation within the base member 14 by means of an elongate, rotatable shaft 18. The upper end of the shaft 18 is connected to a motor 20. The base member 14 includes an outlet passageway connected to a riser 24. A flanged pipe 26 is connected to the upper end of the riser 24 for discharging molten metal into a spout or other conduit (not shown). The pump 10 thus described is so-called transfer pump, that is, it transfers molten metal from the vessel 12 to a location outside of the vessel 12.
Currently, many metal die casting facilities employ a main hearth containing the majority of the molten metal. A transfer pump is located in a well adjacent the main hearth. The transfer pump draws molten metal from the well in which it resides and transfers it into a conduit and from there to die casters that form the metal articles. The present invention relates to pumps used to transfer molten metal from a furnace to a die casting machine, ingot mould, DC caster, ladle or the like.
Aluminum production has been ongoing for over a century and is still going strong. One of the key factors in the success of aluminum is its recyclability. In fact, recycling has proven so valuable—both economically and ecologically—that recover and recycling has become its own industry, and a highly successful one at that. A common practice since the early 1900s, recycling was a low-profile activity until 1968 when recycling of aluminum beverage cans vaulted the industry into public consciousness. Forty years later, aluminum recycling is supported by a national infrastructure, and by a national mindset that recognizes the importance, value, and ease of aluminum recycling. The aluminum recycling industry has invested hundreds of millions of dollars developing a system of more than 10,000 recycling center nationwide. Sources for recycled aluminum include automobiles, windows and doors, appliances and other products.
In many of these applications an aluminum recycling facility and/or a die cast facility may be required to provide cast aluminum in sizes varying from a few pounds to several thousand pounds. For example, aluminum can be cast into steel deoxidizer products. These aluminum cast products are used as an alloying agent in steel to facilitate deoxidation and also refine the grain. These products may take the form of various shapes, including shot, cone, star, or pyramid. Typically, these forms will provide an article which is less than about 100 lbs. in weight. Alternatively, aluminum is cast into T-bar and/or sow type products. Once cast, the T-bar and sow can be transported easily to a location where it will be remelted and cast into an end product. T-bar and sow products can weigh in excess of 100 lbs.